Improvement in tanning



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O l O IVO A, O i0 o :w O O Y o VO O O MO VO 0 i O Am o O O O L O O To MO O TO WO O O ,W .i .u HJW. MM m5 m UNITED STATES HENRY W. ADAMS, OF IRVINGTON, NEW JERSEY.

IMPROVEMENT IN TANNING.

Specification forming part of Letters Patent No. 50,998, dated November 21, 1865.

To all whom it may concern:

Be it known that I, HENRY W. ADAMS, of Irvington, in the county of Essex and State of New Jersey, have invented a new and Improved Tanning Apparatus; and I do hereby declare that the 'ollowin g is a full, clear, and exact description thereof, which will enable others skilled in the art to make and use the same, reference being had to the accompanying drawings, forming forming part of this specitication, in whichu Figure 1 is a top or plan View of my improved apparatus. Fig. 2 is a vertical longitudinal section through the line c m, Fig. 1. Fig.3 isadetail view, partlyin section, through the line y y, Fig. 1.

The tissues ot' skins consist ot' albumcn and gelatine united in various proportions, and each presenting various degrees of condensation of texture. The action of reagents on gelatine is of high interest. W'hen acted upon by chlorine gelatine is converted into a tlocculent substance insoluble in water, but dissolved by an excess of gelatine. Gelatine is not precipitated by alum; but if a solution of common salt be mixed therewith the gelatine falls down, combined with alumina, as it decomposes the muriate of alumina which is then formed. On this principle is founded the manufacture of white leather by akind of tanning with alum. The most important compound of gelatine is that with tannic acid, which constitutes ordinary leather. This reaction is so distinct that one part ot'gelatine in tive thousand of water is at once detected by the infusion of galls. The constitution of the precipitate varies according as one or other of these materials is employedin excess, the tannic acid and gelatine being capable of uniting in at least three difterent proportions. One hundred parts of dry gelatine combine with one hundred and thirty-six parts of tannic acid when the latter is in great excess. This compound contains an atom of each ingredient. Hot water dissolves gelatine, consequently skins cannot be tanned in warm or hot solutions of tannic acids or salts without destroying the toughness of the leather. It consists, in such cases, of soluble gelatine precipitated by tannic acid in powder in the interstices of the skin,which is devoid of strength. As skins, therefore, must be tanned at a temperature below blood-heat in order to cause the tannin to combine with the gelatinous tissues prior to their solution by heat, it has hitherto required a very long time to penetrate skins with tanning substance in sucient quantities to tan thoroughly their interior portions. The outer surfaces in contact with the tanningliquors appear to tan moderately quick, and then retard the interpenetration ot' the tanning-bath by closing up their pores, in consequence of the expansion and enlargement ot' the tanned tissues. The time thus required varies from four months to three years, accord ing to the thickness of the skin and the temperature of the liquor.

Believing that chemical combinations requre no time to form when proper conditions are secured, one of which is absolute contact of the combining elements at a suitable temperature, I have labored industriously to ascertain these precedent conditions and supply them, on a practical scale, for the purpose of securing a much greater expedition in tanning leather without sacriicing any of its highest qualities. I perceived in my experiments that skins soaked in any kind of tanning solutions absorb into their pores this solution, the tannin of which combines with the gelatinous tis sues and leaves the water from which the tan` nin has been extracted still lling the pores of the skin, and preventing more'ot' the richer solution in contact with its exterior surfaces from entering with fresh supplies of tannin for the gelatine of the interior tissues.' It seemed to me if I could remove this exhausted water from the interior and let in more ofthe outside liquor, richer in tannin, I should supply one ot the necessary conditions of rapid tanning. Thisu appears to be a most rational conclusion, when it is considered that it takes one hundred and thirty-six parts of dry tannic acid to saturate or combine with one hundred parts of dry gelatine. This great amount of tannin cannot rapidly work its way by the vehicle of Water from the outside through the closed up exterior pores and tanned surfaces into the interior of the skin, which is at the same time iilled with the spent liquor. I took a clothes-wrin ger and fastened it to a water-pail and filled the pail parn tially full oil a solution of tannic acid, and then soaked a portion of the pate of an ox, from which the hair had been removed by a tanner at my request, and passed it through the rollers. After doing this a few times I was surprised to see how supple they piece had become and how rapidly it was tanning. After working it more or less by saturating and wringing for about fourteen hours I wrun g it and washed and wrung it in clean water until I had washed out all uncombined tannin. I dried it and took it to practical tanners and shoernakers, who, on examination, universally declared it to be perfectly tanned, and to be the first quality of leather. I then had a shoemaker work it into soles and put them on a pair of shoes. He said he never worked finer, tougher, or more perfect leather. I continued these experiments until the demonstration became clear that a calfs skin can be tanned in one hour, and an oxs hide in twcntyfour hours, by this process. My experiments were made in my cellar with liquor at the common temperature, which could not have been higher than 60@ Fahrenheit. On a careful observation and consideration I am satisfied that the rollers, between which the skins are passed and squeezed or wrun g, perform three very im portant offices. They stretch out or pull the skins and prepare them for the quick penetration of the tanning liquor; they squeeze out the spent water from their pores and thus prepare them for the impenetration and reception ot' fresh supplies ot' tannin, and they cause the liquor to flow horizontally 'hefore them through the interior of the skin and y rapidly, but is rendered remarkably supple and tough.

To make this process more practical and cxpeditious on a large scale, I employ severalv sets of wringers at aproperdistance from each other, working under the surface of the tanning-liquor, so that the wringing, pulling, and resaturating process may be going on at the same time, placing the end wrin gers above the tanning-liquor so as to wring each skin as it Vcomes through, and throw it on the platform of rollers, to be removed or to be dropped into the liquor again at the end of the vat. I do not confine myself to this precise use of the wrin gers. They may all work above the surface of the tanning-liquor or all below, and the same general results may be accomplished. One skin may be put in and worked forward and backward between the rollers before itis discharged; or many skins may be passed successively through them and be landed in the opposite end of the vat, when the motion of the wringers may be reversed, and they may be returned through the rollers to the other end. Practice will determine what motions are best. The wringers are adjusted by screws or springs, similar to other wringers, for the purpose ot allowing the skins, as they swell up and grow thicker by the absorption and combination with tannin, to pass between them. White leather maybe tanned by this process by the use ot' alum and salt, or other salts or tanning or curing substances.

The highest strength of tanning-liquors employed by tanners generally is about 120 of the barkometer. They commence with much weaker solutions. I can use much stronger liquors, because my process forces them equally well through the skins. I have used liquors marking 2000, and even more, on the harkometer. Ihe only condition necessary is to re-enforce the strength ot' the tanning-bath by fresh tannin, so as not to allow the bath to fall below its original strength. This is best done by dissolving dry tannin or salts from time to time in the vat, as the liquor grows weaker by the process of tanning.

A is the vat which contains the tanning liquor, and within which are placed the rollers B G D E F, which rollers extend across the vat and revolve in bearings in its sides, Ono end of the axles of the rollers B G D E revolve in bearings placed in recesses cut into the inner side of said vat and do not extend through, thus dispensing with the use of stuifing-boxes and packing at that end of the axles. `llheother ends of the axles ofthe Said` t t rollers pass through the side et' the vat, for convenience in attaching the necessary gear ing for imparting motion. At this end of the rollers the axles must pass through and re volve in stuffing-boxes the rubber or other packing of which will prevent the passage and resist the action of the tanning-liquors. The bearings of the upper row or series of rollers G E must also be made adjustable, so that the rollers can u accommodate themselves to the different thicknesses of the skins that may be passed between them and the lower series, either by screws G or springs or their equivalent. rLhe rollers are also covered with rubber or other tlexible and elastic substance, which,

by yielding, may more readily allow the skins to pass between the upper and lower series, while at the same time exerting sufcient pressure to squeeze the spent liquor therefrom.

To the projecting ends of the upper series of rollers, E C, are attached gear-wheels' H, which mesh into gear-wheels I, attached to the projectin g axles of the lower series of rollers, D B. Motion is communicated from the shaft J by means of the bevel-gears K to the rollers B, which, in turn, by means of the gear-wheels I H, transmit the motion to therollers C. The two outer rollers, B, by means of the pulleys L and bands M, transmit the motion to the rollers D, and they by means of the gearwheels I H impart motion to the rollers E. Thus by the revolution of the shaft J uniform motion is given to all the rollers. The pairs of rollers B C are so placed that the skins, while passing between them, shall be con@ stantl y beneath the surface of .the tannin g-liquor; but the end pairs, D E, are more elevated, so that the skins, while passing between them, shall be above the surface of the tanningfliquor, being delivered upon the platform of rollers F, with the liquor wrun g or squeezed out.

N are perforated boards or platforms extending between each pair of rollers in the manner represented in Fig. 2, and intended to serve as guides and supports to the skins in their passage from one pair of rollers to another, during which passage they become saturated with the tanning-liquor, to have it again wrung or squeezed out by the next pair of rollers. The boards or platforms N are perforated, to allow a free circulation of the tanning-liquor from and to the skins during their passage, and their ends are firmly secured to the sides of the vat. A quantity of skins having been placed in the vat they are removed therefrom singly by the tanners to the platform F atene end of the system of rollers, 'and immediately placed in a position to pass evenly between the end pair of rollers; thence they will pass automatically through the entire series of pairs and be delivered upon the platform at the other end of the vat, to be again returned to the vat, or returned through the rollers, the direction of whose motion may bechanged for this purpose by any of the ordinary means for changing the direction of motion. The platform F is made of rollers for convenience in handling and feeding the hides and in delivering them automatically from the system of rollers through which they have passed.

Zinc or other metal galvanized with zinc should be used whenever metal isreqnired for journals, bearings, stuffing-boxes, linings, Sac., in contact with the tanningliquor, for the reason that tannic acid does not precipitate the salts of zinc.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. The use of one or more pairs of rollers or wringers, B C, for forcing tanning-liquor into 'skins or leather, driving it before them horizontally, or otherwise, through the pores of the same in contact with the gelatinous tissues, squeezing out the partially-spent saturatingliquor, stretching, pulling, working, and wringing them, substantially in the manner and for the purposes hereinbefore set forth.

2. The mechanical construction and use of the tan-vat, in combination with the wringing and stretching rollers B C D E, or either of them, substantially in the manner and for the objects stated.

3. The feed rollers or tables F, in combination with the wringing and stretching rollers B G D E, or either of them, substantially in the manner and for the objects named.

4. The wringing rollers D E, which work above-the tanning-liquor, in combination with the wringers and stretchers B G, which work below it, substantially in the manner and for the purposes specified.

5. The use ofzinc, or other metal galvanized with zinc, for linings, journals, bearings, stuffing-boxes, and other useful purposes, in contact with tannic acid, when employed in the vat for tanning leather, substantially as described, and for the purposes set forth.

6. 'lhe guides N, by and between which the skins pass from one pair of rollers to the nextfollowing pair, in combination with the said rollers or wringers, substantially as described, and for the purposes set forth.

7. The use of stufling-boXes in combination with the ends of the rollers which pass through the side of the tan-vat, for the purpose of preventing leakage ofthe tannin g-liquor, substantially as described.

8. The screws G, or their equivalent, in combination with one roller of each pair when the said rollers are employed for tanning leather, substantially as set forth, for the purpose of adjusting the space between the rollers of each pair to accommodate different thicknesses of skins and the increasing thickness of the same skin as the process of tanning advances.

9. The use of india-rubber or equivalent flexible and yielding substance around the rollers or wringers, when the said wrin gers or rollers are employed for tanning or wringing skins or leather, but not otherwise, for the purpose of accommodating the space between the said rollers of each pair to the differentthicknesses of the same skin, substantially as described.

10. rlhe entire mechanical process of expeditiously tanning leather substantially in the manner herein set forth.

HENRY W. ADAMS.

Witnesses:

M. M. LIVINGSTON, G. L. TOPLIFF. 

